JP2000147280A - Wavelength correction method of optical multiplexer / demultiplexer - Google Patents

Abstract

(57) [Problem] To provide a wavelength correction method for an optical multiplexer / demultiplexer that can improve the production yield of the optical multiplexer / demultiplexer and can reduce the cost. SOLUTION: A plurality of arrayed waveguides formed of a glass material and having different lengths are juxtaposed, and light having a plurality of different wavelengths is multiplexed by the arrayed waveguides or a plurality of wavelengths different from each other are provided. An optical multiplexer / demultiplexer is formed by an arrayed waveguide type diffraction grating that splits light of one or more wavelengths from light. The center wavelength of the light multiplexed by the array waveguide or the center wavelength of the light multiplexed by the optical multiplexing / demultiplexing unit is a predetermined setting wavelength as shown by a characteristic line a.
(1550 nm) at a wavelength shorter than the glass transition temperature of the glass material, e.g.
By heating for 6 hours, as shown by the characteristic line b, the respective center wavelengths of the light multiplexed by the array waveguide and the light multiplexed by the optical multiplexing / demultiplexing unit are corrected to the longer wavelength side to obtain the set wavelength. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical multiplexer / demultiplexer for correcting a multiplexing wavelength and a demultiplexing wavelength of an optical multiplexer / demultiplexer used in, for example, a wavelength division multiplexing optical transmission system.

[0002]

2. Description of the Related Art In recent years, in optical communications, research and development on optical wavelength division multiplexing has been actively conducted as a method for dramatically increasing the transmission capacity, and practical use thereof has been progressing. Optical wavelength division multiplexing is, for example, a method of multiplexing and transmitting a plurality of lights having different wavelengths. In such an optical wavelength division multiplexing communication system, an optical multiplexing method of multiplexing lights of a plurality of different wavelengths is used. It is indispensable in the system to provide an optical multiplexer / demultiplexer having a function and an optical demultiplexer function for demultiplexing light of one or more wavelengths from transmitted light having a plurality of different wavelengths.

As an example of an optical multiplexer / demultiplexer, for example, an arrayed waveguide type diffraction grating (A) utilizing an interference effect or a diffraction effect of light.
WG; Arrayed Waveguide Grat
), a Mach-Zehnder interference type element, a ring resonance type filter, an optical multiplexer / demultiplexer equipped with a Fabry-Perot etalon and the like are currently used.

[0004]

In order to use the above-described optical multiplexer / demultiplexer in a wavelength division multiplexing optical transmission system, for example, when combining lights of a plurality of wavelengths different from each other, a predetermined wavelength is required. When light of one or more wavelengths is demultiplexed by an optical multiplexer / demultiplexer from light having a plurality of different wavelengths to be surely multiplexed, or to be transmitted, light having a plurality of different wavelengths. Considerable wavelength accuracy is required, for example, to surely split light of the set wavelength.

However, due to a manufacturing error or the like in manufacturing the optical multiplexer / demultiplexer as described above, an error occurs in the wavelength of light multiplexed by the optical multiplexer / demultiplexer or the wavelength of light demultiplexed by the optical multiplexer / demultiplexer. Often occurs, and it has been difficult to produce an optical multiplexer / demultiplexer capable of reliably multiplexing the light of the set wavelength or reliably splitting the light of the set wavelength. Therefore, conventionally, the production yield of the optical multiplexer / demultiplexer as described above is low, which causes a problem that the price of the optical multiplexer / demultiplexer is increased.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to improve the production yield of an optical multiplexer / demultiplexer and thereby reduce the cost of the optical multiplexer / demultiplexer. It is an object of the present invention to provide a wavelength correction method for an optical multiplexer / demultiplexer that can perform the above-described operations.

[0007]

In order to achieve the above-mentioned object, the present invention has the following structure to solve the problem. That is, the first invention has an optical multiplexing function of multiplexing light of a plurality of different wavelengths and an optical multiplexing function of demultiplexing light of one or more wavelengths from light having a plurality of different wavelengths. It has an optical multiplexing / demultiplexing part having at least one function, and the optical multiplexing / demultiplexing part is formed by a plurality of optical waveguides formed of a glass material and having different lengths from each other, and is multiplexed by the optical multiplexing / demultiplexing part. A wavelength correction method for an optical multiplexer / demultiplexer, wherein each central wavelength of light to be demultiplexed with light is proportional to a difference between the lengths of the optical waveguides and an effective refractive index of the optical waveguide. When the center wavelength of the divided light or the center wavelength of the light demultiplexed by the optical multiplexing / demultiplexing unit is on the shorter wavelength side than a predetermined setting wavelength, at least the optical multiplexing / demultiplexing unit is set to the glass at room temperature or higher. Pre-set at a temperature below the glass transition temperature of the material As a means for solving the problem, a configuration in which each central wavelength of light multiplexed by the optical multiplexing / demultiplexing unit and light demultiplexed by the optical multiplexing / demultiplexing unit is corrected to a longer wavelength side by heating only for the heating time determined. I have.

In the second invention, a first slab waveguide is connected to an output side of one or more optical input waveguides arranged in parallel, and an output side of the first slab waveguide is connected to an output side of the first slab waveguide. A plurality of side-by-side arrayed waveguides of different lengths for transmitting light derived from the first slab waveguide are connected, and a second slab waveguide is provided on an output side of the plurality of arrayed waveguides. The second slab waveguide has a waveguide pattern formed by connecting one or more optical output waveguides arranged side by side on the output side, and an optical multiplexing / demultiplexing unit is formed by the array waveguide. The formed arrayed waveguide type diffraction grating is used as an optical multiplexer / demultiplexer, and has a configuration in which the wavelength of light multiplexed or demultiplexed by the arrayed waveguide is corrected using the wavelength correction method of the first aspect of the present invention. It is a means to solve the problem.

Further, in the third invention, a first directional coupler is connected to an output side of the optical input waveguide, and the first directional coupler is connected to an output side of the first directional coupler. Two side-by-side arm waveguides of different lengths for transmitting light derived from the coupler are connected, and a second directional coupler is connected to the output side of the two arm waveguides. An output side of the second directional coupler has a waveguide pattern formed by connecting an optical output waveguide, and a Mach-Zehnder interference type element in which an optical multiplexing / demultiplexing section is formed by the arm waveguide is provided. The optical multiplexer / demultiplexer is a means for solving the problem by a configuration in which the wavelength of light multiplexed or demultiplexed by the arm waveguide is corrected by using the wavelength correction method of the first invention.

Further, in the present invention, an optical input waveguide and an optical output waveguide are connected to a ring type optical waveguide formed of a glass material via a directional coupler. A ring resonator type filter whose resonance wavelength is proportional to the length of the ring type optical waveguide and the effective refractive index of the ring type optical waveguide is different from the resonance wavelength of the ring type optical waveguide from light of a plurality of different wavelengths. A wavelength correction method for an optical multiplexer / demultiplexer that splits light having a wavelength, wherein when a resonance wavelength of the ring-type optical waveguide is on a shorter wavelength side than a predetermined set wavelength, at least the ring-type optical waveguide is used. By heating a predetermined heating time at a temperature equal to or higher than room temperature and equal to or lower than the glass transition temperature of the glass material, the resonance wavelength of the ring-type optical waveguide is corrected to a longer wavelength side. It is a means to solve the problem.

Further, the fifth invention has a Fabry-Perot etalon in which mirrors are provided on both sides of a substrate formed of a glass material and reflection surfaces of these mirrors are opposed to each other. Is proportional to the distance between the reflecting surfaces of the mirror and the effective refractive index of the substrate,
A wavelength correction method for an optical multiplexer / demultiplexer for demultiplexing light having a wavelength different from the resonance wavelength of the Fabry-Perot etalon from light having a plurality of different wavelengths, wherein the resonance wavelength of the Fabry-Perot etalon is a predetermined wavelength. When it is on the shorter wavelength side, by heating at least the Fabry-Perot etalon at a temperature equal to or higher than room temperature and equal to or lower than the glass transition temperature of the glass material for a predetermined heating time,
This is a means for solving the problem by a configuration for correcting the resonance wavelength of the Fabry-Perot etalon to the longer wavelength side.

The optical multiplexer / demultiplexer of the optical multiplexer / demultiplexer according to the first aspect of the present invention, the arrayed waveguide type diffraction grating to which the wavelength correcting method according to the second aspect of the present invention is applied, and the optical waveguide according to the third aspect of the present invention. The central wavelengths of light to be multiplexed and demultiplexed by an optical multiplexing / demultiplexing unit such as a Mach-Zehnder interference type element to which the wavelength correction method is applied are determined by the difference between the length of the optical waveguide forming the optical multiplexing / demultiplexing unit and the optical waveguide. The central wavelengths of the light to be multiplexed and demultiplexed by the optical multiplexing / demultiplexing unit are changed by varying the effective refractive index of the optical multiplexer / demultiplexer.

In general, it is known that when a glass material is heated at a constant temperature near the glass transition temperature, the volume of the glass material shrinks or expands depending on whether the state before heating is smaller or larger than the equilibrium state. Has been
By heating at a temperature lower than the glass transition temperature, the volume of the glass material shrinks, and the effective refractive index of the glass material increases, so that the optical multiplexing / demultiplexing unit as in the first to third inventions described above. When the center wavelength of the light multiplexed by the light or the center wavelength of the light demultiplexed by the optical multiplexing / demultiplexing unit is on the shorter wavelength side than a predetermined setting wavelength, at least the optical multiplexing / demultiplexing unit is at room temperature or higher. When the glass material is heated at a temperature equal to or lower than the glass transition temperature of the glass material, the respective center wavelengths of the light multiplexed at the optical multiplexing / demultiplexing part and the light demultiplexed at the optical multiplexing / demultiplexing part shift to longer wavelengths.

In the first, second and third inventions, the center wavelength of the light multiplexed by the optical multiplexing / demultiplexing unit or the center wavelength of the light demultiplexed by the optical multiplexing / demultiplexing unit is predetermined. When the wavelength is shorter than the set wavelength, by heating for a predetermined heating time, each central wavelength of the light to be multiplexed by the optical multiplexing / demultiplexing unit and the light to be demultiplexed by the optical multiplexing / demultiplexing unit is set. Since the correction is performed on the long wavelength side, by appropriately setting the heating time, the center wavelength can be corrected to the set wavelength or a wavelength close to the set wavelength, so that the production yield of the optical multiplexer / demultiplexer is improved. Thus, the cost of the optical multiplexer / demultiplexer can be reduced.

Similarly, in the fourth invention,
When the resonance wavelength of the ring-shaped optical waveguide is on the shorter wavelength side than a predetermined set wavelength, at least the ring-shaped optical waveguide is heated at a temperature equal to or higher than room temperature and equal to or lower than a glass transition temperature of the glass material. By heating only for a time, the resonance wavelength of the ring-type optical waveguide is corrected to a longer wavelength side. In the fifth aspect of the invention, the resonance wavelength of the Fabry-Perot etalon is shorter than a predetermined setting wavelength. When on the wavelength side, by heating at least the Fabry-Perot etalon at a temperature equal to or higher than room temperature and equal to or lower than the glass transition temperature of the glass material for a predetermined heating time, the resonance wavelength of the Fabry-Perot etalon is shifted to the longer wavelength side. In any of the inventions, by appropriately setting the heating time,
Since the resonance wavelength can be corrected to the set wavelength or a wavelength close to the set wavelength, the production yield of the optical multiplexer / demultiplexer is improved, and the cost of the optical multiplexer / demultiplexer can be reduced.
The above problem is solved.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a main configuration of an optical multiplexer / demultiplexer to which the first embodiment of the wavelength correcting method for an optical multiplexer / demultiplexer according to the present invention is applied.

As shown in FIG. 1, this optical multiplexer / demultiplexer is an arrayed waveguide type diffraction grating, and is provided as a first slab waveguide on the output side of one or more optical input waveguides 2 arranged in parallel. Of the input side slab waveguide 3 are connected.
Are connected to a plurality of arrayed waveguides 4 that propagate light derived from the input-side first slab waveguide 3, and the output side of the plurality of arrayed waveguides 4 is connected to the second slab. The output side slab waveguide 5 as a waveguide is connected, and the output side of the output side slab waveguide 5 has a waveguide pattern formed by connecting one or more optical output waveguides 6 arranged in parallel. ing.

The array waveguides 4 are formed side by side with different lengths made of a glass material. These array waveguides 4 have an optical multiplexing function for multiplexing light of a plurality of different wavelengths. An optical multiplexing / demultiplexing unit 10 having an optical demultiplexing function of demultiplexing light of one or more wavelengths from light having a plurality of different wavelengths is formed.

The array waveguide 4 usually has, for example, 1
The optical input waveguide 2 and the optical output waveguide 6 are provided in a large number such as 00, for example, in accordance with the number of lights of different wavelengths to be multiplexed or demultiplexed by the arrayed waveguide 4, for example. In this figure, the arrayed waveguides 4 and 16 are provided for simplifying the drawing.
The number of optical input waveguides 2 and optical output waveguides 6 is shown in a simplified manner. The arrayed waveguide type diffraction grating shown in FIG.
Each waveguide including the array waveguide 4 is formed of a glass material.

An optical fiber on the transmission side, for example, is connected to the optical input waveguide 2, and as shown in FIG. 1, wavelengths having lights (λ1, λ2, λ3,... Λn) having different wavelengths are provided. When the multiplexed light is introduced, the light that has passed through the optical input waveguide 2 is introduced into the input side slab waveguide 3, and the light spreads due to its diffraction effect and enters each of the plurality of arrayed waveguides 4, and each of the arrayed waveguides 4 The light propagates through the waveguide 4.

The light propagating through each array waveguide 4 reaches the output side slab waveguide 5 and is further condensed and output by the optical output waveguide 6, but the length of each array waveguide 4 is reduced. Since they are different from each other, a phase shift of each light occurs after propagating through each array type waveguide 4, and the wavefront of the converged light is tilted according to the amount of the shift, and the position of condensing is determined by the tilt angle. Lights having different wavelengths are condensed at different positions, and by forming the optical output waveguide 6 at that position, for example, as shown in FIG.
(λ1, λ2, λ3,... λn) are output from the different optical output waveguides 6 for each wavelength.

Further, since the light has reversibility, for example, when a plurality of lights having different wavelengths are made to enter from the respective optical output waveguides 6, the light propagates in a direction opposite to the above. Along the path, multiplexed by the array waveguide 4,
The light is emitted from the optical input waveguide 2.

As described above, in the arrayed waveguide type diffraction grating, multiplexing and demultiplexing of light are performed by the array waveguide 4 utilizing the diffraction effect of light. Each center wavelength of the emitted light is proportional to the difference between the lengths of the arrayed waveguides 4 and the effective refractive index of the arrayed waveguides 4. Specifically, the center wavelength λa of light that is multiplexed or demultiplexed by the array waveguide 4 is determined by the difference ΔL between the lengths of the plurality of array waveguides 4 and the effective refractive index n of the array waveguide 4. , Diffraction order m
(The diffraction order m is an integer and is constant),
Expressed by (1), the optical path length difference ΔL of the arrayed waveguide 4
Is an integral multiple of the center wavelength.

M · λa = n · ΔL (1)

The array waveguide type diffraction grating shown in FIG. 2 was specifically manufactured as follows. That is, a quartz glass is formed on a silicon substrate 1 using a flame deposition method and reactive ion etching, the size of a core forming each waveguide is 6 μm × 6 μm, and the refractive index of the core is:
The refractive index of the lower clad provided on the lower side of the core and the refractive index of the upper clad provided on the upper side of the core were 0.75% larger.

Further, the length difference (optical path length difference) ΔL of the arrayed waveguide 4 is set to 64 μm, whereby the wavelength 1.55 μm which is a wavelength region used in the wavelength division multiplexing optical transmission system is obtained.
In the m band, it was formed so that light having a wavelength interval of 0.8 nm could be multiplexed or demultiplexed. When the light is split by the arrayed waveguide grating, one of the split lights has a center wavelength of 1550 nm.

Next, a method for correcting the wavelength of the optical multiplexer / demultiplexer according to this embodiment will be described. In the wavelength correction method according to the present embodiment, the center wavelength of light multiplexed by the array waveguide 4 forming the optical multiplexing / demultiplexing unit 10 or the center wavelength of light multiplexed by the array waveguide 4 is determined in advance. When the wavelength is shorter than the set wavelength, the wavelength is corrected.

For this correction, in this embodiment, first, the wavelength characteristics of the light emitted from each light output waveguide 6 of the arrayed waveguide type diffraction grating were measured. Since the wavelength characteristics of the light emitted from each optical output waveguide 6 correspond to the wavelength characteristics of the light demultiplexed by the array waveguide 4, the wavelength characteristics of the light emitted from each optical output waveguide 6 Is measured, the wavelength characteristic of the light split by the array waveguide 4 can be known. Further, as described above, the array waveguide type diffraction grating has different wavelengths from the light output waveguide 6 side. When a plurality of lights are input, these lights are multiplexed by the array waveguide 4 and output from the optical input waveguide 2, so that the wavelength characteristics of the light multiplexed by the array waveguide 4 are also You can know.

The characteristic line a in FIG. 1 shows that one of the light output waveguides 6 (ports) of the arrayed waveguide type diffraction grating shown in FIG. 4 shows wavelength characteristics of emitted light. The array waveguide type diffraction grating has a center wavelength of light emitted from this port of 1550.
However, due to a process error of the flame deposition / reactive ion etching, the effective refractive index of the arrayed waveguide type diffraction grating is shifted, and the wavelength characteristic is 1550 nm which is the set wavelength. 0.12 nm to the shorter wavelength side.

The array waveguide 4 is formed of a glass material. When the glass material is heated at a constant temperature near the glass transition temperature and lower than the glass transition temperature, the volume of the glass material shrinks, and the effective amount of the glass material is reduced. Since the refractive index increases, when the array waveguide 4 is heated at a temperature near the glass transition temperature of the glass material and lower than the glass transition temperature, the effective refractive index of the array waveguide 4 increases, and the above formula ( According to 1), the center wavelength of the light split or combined by the array waveguide 4 shifts to the longer wavelength side.

In this embodiment, utilizing this fact,
As described above, when the wavelength of the light demultiplexed by the array waveguide 4 deviates from the set wavelength to the shorter wavelength side, at least the array waveguide 4 is at room temperature or higher and the glass transition temperature of the glass material is 900 ° C. By heating at a temperature of 700 ° C. below for a predetermined heating time, the respective center wavelengths of the light multiplexed and the light demultiplexed in the arrayed waveguide 4 are corrected to the longer wavelength side.

At the time of the heating, a test array waveguide type diffraction grating having the same configuration as that of the array waveguide type diffraction grating to which the present embodiment is applied is used, and the array waveguide of this test array waveguide type diffraction grating is used. 4 was heated at 700 ° C., the relationship between the heating time and the shift amount of the center wavelength of the light emitted from each port was measured in advance. The result is shown in FIG. 3, and as is clear from FIG.
Is heated at 700 ° C. for 96 hours to bring the center wavelength to 0.1.
It turned out that it can shift to 11 nm long wavelength side.

Therefore, in this embodiment, the array waveguide 4 of the arrayed waveguide type diffraction grating shown in FIG. 2 is heated at 700 ° C. for 96 hours, and the light split by the arrayed waveguide type diffraction grating is emitted. The wavelength of the multiplexed light is corrected. As a result, the wavelength characteristic of the light emitted from the port in the arrayed waveguide type diffraction grating after the correction by the wavelength correction method of the present embodiment is shifted to the longer wavelength side as shown by the characteristic line b in FIG. And its central wavelength is 1550 nm
It became the set wavelength. Similar results were obtained for the other ports, and the center wavelengths of all the ports were set wavelengths.

According to this embodiment, as described above, the center wavelength of the light multiplexed by the array waveguide 4 or the center wavelength of the light demultiplexed by the array waveguide 4 is set to a predetermined set wavelength. By heating for a predetermined heating time when the wavelength is shorter than the shorter wavelength side, each central wavelength of the light multiplexed by the array waveguide 4 and the light demultiplexed by the array waveguide 4 is shifted to the longer wavelength side. By appropriately setting the heating time, the respective center wavelengths can be corrected to the set wavelength.

Therefore, the production yield of the optical multiplexer / demultiplexer formed by the arrayed waveguide type diffraction grating is improved by correcting each of the center wavelengths to the set wavelength using the wavelength correction method of the embodiment. Thus, the cost of the optical multiplexer / demultiplexer can be reduced.

FIG. 4 shows an optical multiplexer / demultiplexer to which the second embodiment of the wavelength correcting method for an optical multiplexer / demultiplexer according to the present invention is applied. In FIG. 4, the same reference numerals are assigned to the same parts as those of the arrayed waveguide type diffraction grating shown in FIG.

The optical multiplexer / demultiplexer shown in FIG.
The first directional coupler 7 is connected to the output side of the first directional coupler 7, and the output side of the first directional coupler 7 has different lengths for transmitting the light derived from the first directional coupler 7. The two arm waveguides 8 arranged side by side are connected, and a second directional coupler 9 is connected to the emission side of the two arm waveguides 8.
The directional coupler 9 has a waveguide pattern formed by connecting an optical output waveguide 6 to an output side thereof, and an optical multiplexing / demultiplexing unit 10 is formed by an arm waveguide 8 (Mach-Zehnder interference type element). Optical element). In addition,
Also in this Mach-Zehnder interference optical element, each optical waveguide including the arm waveguide 8 is formed of a glass material.

In such a Mach-Zehnder interference optical element, for example, as shown in FIG.
By propagating the light into the arm waveguides 8, the light is output to the different optical output waveguides 6 (6 a, 6 b),
In addition, since light has reversibility, for example, when a plurality of lights having different wavelengths from each light output waveguide 6 are incident from the respective optical output waveguides 6, these lights are The light is multiplexed by the arm waveguide 8 through the propagation path opposite to the above, and is emitted from the optical input waveguide 2.

By the way, the wavelength λb of the light to be multiplexed or demultiplexed according to the operation principle of the Mach-Zehnder interference optical element,
λc satisfies the following equations (2) and (3).

M · λb = n · ΔL (2)

(M + ／) · λc = n · ΔL (3)

In the above equations (2) and (3), ΔL
Is the difference between the lengths of the arm waveguides 8, n is the effective refractive index of the arm waveguide 8, m is the diffraction order, and the diffraction order m is an integer and constant.

As is apparent from these equations, the central wavelengths of the light multiplexed and the light demultiplexed by the Mach-Zehnder interference optical element are determined by the difference in the length of the arm waveguide 8 and the effective refraction of the arm waveguide 8. It is proportional to the rate.

Therefore, in the present embodiment, when the wavelength of the light to be multiplexed or demultiplexed by the arm waveguide 8 is shorter than a predetermined set wavelength, at least the arm waveguide 8 is By heating for a predetermined heating time at a temperature equal to or higher than room temperature and equal to or lower than the glass transition temperature of the glass material, each central wavelength of the light multiplexed in the arm waveguide 8 and the light multiplexed in the optical multiplexing / demultiplexing unit. Was corrected to the longer wavelength side.

In this embodiment, the arm waveguide 8
Is set to 700 ° C. in the same manner as the heating time of the arrayed waveguide type diffraction grating in the first embodiment, and a test Mach-Zehnder interference element is used in the same manner as in the first embodiment. The relationship between the heating time of the arm waveguide 8 at 700 ° C. and the wavelength shift amount is obtained in advance,
The heating time of the arm waveguide 8 was set based on the relation data.

Also in this embodiment, the respective center wavelengths of the light multiplexed by the arm waveguide 8 and the light multiplexed by the arm waveguide 8 which are optical multiplexing / demultiplexing portions of the Mach-Zehnder interference optical element are predetermined. When the center wavelength is shorter than the set wavelength, the same effect as in the first embodiment can be obtained by correcting each center wavelength to the longer wavelength side as in the first embodiment. .

FIG. 5 shows an optical multiplexer / demultiplexer to which the third embodiment of the wavelength correcting method for an optical multiplexer / demultiplexer according to the present invention is applied. 5, the same reference numerals are given to the same components as those of the arrayed waveguide type diffraction grating shown in FIG. 2 and the Mach-Zehnder interference type device shown in FIG.

The optical multiplexer / demultiplexer shown in FIG. 5 includes a directional coupler 1 and a ring type optical waveguide 11 formed of a glass material.
2 is an optical multiplexer / demultiplexer provided with a ring resonator type filter 16 in which the optical input waveguide 2 and the optical output waveguide 6 are connected via the optical waveguide 2, and light of a plurality of wavelengths different from each other (in FIG.
From the wavelengths λ1, λ2) to the resonance wavelength of the ring type optical waveguide 11.
The light (wavelength λ2 in the figure) having a different wavelength (in the figure, wavelength λ1) is demultiplexed and output from the optical output waveguide 6.

According to the operation principle of the ring resonator type filter 16, the resonance wavelength of the ring resonator, that is, the resonance wavelength λd of the ring type optical waveguide 11, is determined by the effective refractive index n of the glass material forming the ring type optical waveguide 11, Using the length n of the ring-type optical waveguide 11 and the diffraction order m (m is an integer and is constant), it is expressed by the following equation (4).

M · λd = n · L (4)

As is apparent from this equation, the resonance wavelength of the ring-shaped optical waveguide 11 is proportional to the length of the ring-shaped optical waveguide 11 and the effective refractive index of the ring-shaped optical waveguide 11.

Therefore, in the third embodiment, when the resonance wavelength of the ring-shaped optical waveguide 11 is shorter than a predetermined set wavelength, at least the ring-shaped optical waveguide 11 is kept at room temperature or higher. By heating at a temperature equal to or lower than the glass transition temperature of the glass material for a predetermined heating time, the resonance wavelength of the ring-shaped optical waveguide 11 is corrected to a longer wavelength.

In this embodiment, the specific heating temperature of the ring type optical waveguide 11 is set to 700 ° C. as in the first embodiment, and the test ring is heated in the same manner as in the first embodiment. Ring type optical waveguide 1 using resonator type filter
The relationship between the heating time at 700 ° C. and the wavelength shift amount of No. 1 was obtained in advance, and the heating time of the ring-type optical waveguide 11 was set based on this relationship data.

Also in the third embodiment, when the resonance wavelength of the ring type optical waveguide 11 is on the shorter wavelength side than the predetermined set wavelength, similar to the first and second embodiments, By correcting the resonance wavelength of the ring type optical waveguide 11 to the longer wavelength side, the same effects as those of the first and second embodiments can be obtained.

FIG. 6 shows an optical multiplexer / demultiplexer to which the fourth embodiment of the wavelength correcting method for an optical multiplexer / demultiplexer according to the present invention is applied. The optical multiplexer / demultiplexer shown in FIG. 1 is provided with mirrors 13 on both sides sandwiching a glass substrate 15 formed of a glass material, and forms a Fabry-Perot etalon 17 in which the reflection surfaces 14 of these mirrors 13 are opposed to each other. And light of a plurality of wavelengths different from each other (wavelengths λ1 and λ2 in the figure).
Therefore, light having a wavelength different from the resonance wavelength of the Fabry-Perot etalon 17 (wavelength λ1 in the figure) (in the figure,
The wavelength λ2) is demultiplexed and output from the optical output waveguide 6.

According to the operation principle of the Fabry-Perot etalon, the resonance wavelength λe of the Fabry-Perot etalon 17 is determined by the effective refractive index n of the glass material forming the glass substrate 15, the distance d between the reflecting surfaces of the mirror 13, and the diffraction order m (m). Is an integer and is constant), and is represented by the following equation (4).

M · λe = n · d (4)

As is apparent from this equation, the resonance wavelength λe
Is proportional to the distance d between the reflecting surfaces of the mirror 13 and the effective refractive index n of the glass material forming the substrate 15.

Therefore, in the fourth embodiment, when the resonance wavelength of the Fabry-Perot etalon 17 is shorter than the predetermined wavelength, at least the Fabry-Perot etalon 17 is heated at room temperature or higher to the glass material. By heating at a temperature equal to or lower than the glass transition temperature for a predetermined heating time, the resonance wavelength of the Fabry-Perot etalon 17 is corrected to a longer wavelength side.

The specific heating temperature of the Fabry-Perot etalon 17 is set to 700 ° C. similarly to the heating of the arrayed waveguide type diffraction grating in the first embodiment.
As in the embodiment, the relationship between the heating time of the Fabry-Perot etalon 17 at 700 ° C. and the amount of wavelength shift is previously determined using the Fabry-Perot etalon for testing, and the heating of the Fabry-Perot etalon 17 is performed based on this relationship data. Set the time.

Also in the third embodiment, when the resonance wavelength of the Fabry-Perot etalon 17 is shorter than the predetermined wavelength, the Fabry-Perot etalon 17 can be used. By correcting the resonance wavelength to the longer wavelength side, the same effects as in the above embodiments can be obtained.

The present invention is not limited to the above-described embodiment, but can adopt various embodiments. For example, in each of the above embodiments, the array waveguide 4 and the arm waveguide 8
And ring type optical waveguide 11 and Fabry-Perot etalon 17
Was heated to 700 ° C., but the heating temperature is not particularly limited. The heating temperature is not higher than the glass transition temperature of the glass material forming each of the optical waveguides 4, 8, 11 and Fabry-Perot etalon 17. The temperature is set to an appropriate temperature equal to or higher than room temperature.

The heating time at this heating temperature is as follows:
At this heating temperature, when the array waveguide 4 and the arm waveguide 8 of the optical multiplexer / demultiplexer having the same configuration as the optical multiplexer / demultiplexer to be heated are heated, the coupling / demultiplexing by the array waveguide 4 and the arm waveguide 8 is performed. It is set in advance based on the shift amount of the center wavelength of the wave or the shift amount of the resonance wavelength of the ring-shaped optical waveguide 11 or Fabry-Perot etalon 17 when the ring-shaped optical waveguide 11 or Fabry-Perot etalon 17 is heated at the heating temperature. You.

The optical multiplexer / demultiplexer to which the wavelength correcting method for an optical multiplexer / demultiplexer according to the present invention is applied is not limited to the optical multiplexer / demultiplexer to which the above embodiments are applied, but may be set as appropriate. The multiplexing center wavelength and the multiplexing center wavelength by the optical multiplexing / demultiplexing portion of the optical multiplexing / demultiplexing device formed by the arrayed waveguide type diffraction grating and the Mach-Zehnder interference type element are appropriately set, and the ring resonance The resonance wavelengths of the filter 16 and Fabry-Perot etalon 17 are appropriately set.

Further, at least one of an optical multiplexing function for multiplexing light having a plurality of different wavelengths and an optical demultiplexing function for demultiplexing light having one or more wavelengths from light having a plurality of different wavelengths. Having an optical multiplexing / demultiplexing part having a plurality of optical waveguides formed of a glass material and having different lengths from each other. The light multiplexing / demultiplexing part is formed of a glass material. As long as each central wavelength is an optical multiplexer / demultiplexer in which the difference between the lengths of the optical waveguides and the effective refractive index of the optical waveguides are used, the present invention is applicable to optical waveguide devices other than arrayed waveguide type diffraction gratings and Mach-Zehnder interference type devices. The invention can be widely applied.

[0066]

According to the first, second and third aspects of the present invention, the center wavelengths of the light to be multiplexed and demultiplexed by the optical multiplexing / demultiplexing unit are equal to those of the optical waveguide forming the optical multiplexing / demultiplexing unit. Since the difference in length is proportional to the effective refractive index of the optical waveguide, the center wavelength of the light multiplexed by the optical multiplexing / demultiplexing unit or the center wavelength of the light demultiplexed by the optical multiplexing / demultiplexing unit is set in advance. When the wavelength is shorter than the wavelength, by heating at least the optical multiplexing / demultiplexing unit at a temperature equal to or higher than room temperature and equal to or lower than the glass transition temperature of the glass material, the volume of the glass material forming the optical multiplexing / demultiplexing unit is reduced. By causing shrinkage and increasing the effective refractive index of the glass material, it is possible to shift each central wavelength of the light multiplexed at the optical multiplexing / demultiplexing part and the light demultiplexed at the optical multiplexing / demultiplexing part to a longer wavelength side. .

Therefore, in the first, second, and third aspects of the present invention, by appropriately setting the heating time, the center wavelength can be corrected to the set wavelength or a wavelength close to the set wavelength. The manufacturing yield of the optical multiplexer / demultiplexer can be improved, and thereby the cost of the optical multiplexer / demultiplexer can be reduced.

Similarly, in the fourth invention,
When the resonance wavelength of the ring-shaped optical waveguide is on the shorter wavelength side than a predetermined set wavelength, at least the ring-shaped optical waveguide is heated at a temperature equal to or higher than room temperature and equal to or lower than a glass transition temperature of the glass material. By heating only for a time, the resonance wavelength of the ring-type optical waveguide is corrected to a longer wavelength side. In the fifth aspect of the invention, the resonance wavelength of the Fabry-Perot etalon is shorter than a predetermined setting wavelength. When on the wavelength side, by heating at least the Fabry-Perot etalon at a temperature equal to or higher than room temperature and equal to or lower than the glass transition temperature of the glass material for a predetermined heating time, the resonance wavelength of the Fabry-Perot etalon is shifted to the longer wavelength side. In any of the inventions, by appropriately setting the heating time,
The resonance wavelength can be corrected to the set wavelength or a wavelength close to the set wavelength.

Therefore, also in the fourth and fifth aspects, the production yield of the optical multiplexer / demultiplexer can be improved, and the cost of the optical multiplexer / demultiplexer can be reduced.

[Brief description of the drawings]

FIG. 1 shows a wavelength characteristic of light emitted from one port of an arrayed waveguide type diffraction grating and a wavelength obtained by applying a wavelength correction method of an optical multiplexer / demultiplexer according to the present invention to the arrayed waveguide type diffraction grating. 5 is a graph showing wavelength characteristics of light emitted from the port when corrected.

FIG. 2 is a first diagram illustrating a wavelength correction method for an optical multiplexer / demultiplexer according to the present invention;
It is a principal part block diagram which shows the arrayed waveguide type diffraction grating to which an embodiment is applied.

FIG. 3 is a graph showing a relationship between a heating time of an arrayed waveguide grating and a shift amount of a center wavelength of demultiplexing of the arrayed waveguide grating.

FIG. 4 is a second diagram illustrating a wavelength correction method for an optical multiplexer / demultiplexer according to the present invention.
It is a principal part block diagram which shows the Mach-Zehnder interference type element to which an embodiment is applied.

FIG. 5 is a third diagram illustrating a wavelength correction method for an optical multiplexer / demultiplexer according to the present invention;
It is a principal part block diagram which shows the ring resonator type filter to which an embodiment is applied.

FIG. 6 shows a fourth method of correcting the wavelength of the optical multiplexer / demultiplexer according to the present invention.
It is a principal part block diagram which shows the Fabry-Perot etalon to which an embodiment example is applied.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 optical input waveguide 3 input side slab waveguide 4 array waveguide 5 output side slab waveguide 6 optical output waveguide 7, 9, 12 directional coupler 8 arm waveguide 10 optical multiplexing / demultiplexing unit 11 ring type optical waveguide Wave path 13 Mirror 14 Reflecting surface 15 Glass substrate 16 Ring resonator type filter 17 Fabry-Perot etalon

Claims (5)

[Claims] An optical multiplexing function for multiplexing light of a plurality of wavelengths different from each other and a function of combining light having a plurality of wavelengths different from each other.
An optical multiplexing / demultiplexing unit having at least one of optical demultiplexing functions of demultiplexing light of two or more wavelengths, wherein the optical multiplexing / demultiplexing unit includes a plurality of optical waveguides formed of a glass material and having different lengths from each other. And a central wavelength of light to be multiplexed and demultiplexed by the optical multiplexing / demultiplexing unit, wherein each center wavelength of the light to be demultiplexed is proportional to a difference in length of the optical waveguide and an effective refractive index of the optical waveguide. In the wavelength correction method, the center wavelength of the light multiplexed by the optical multiplexing / demultiplexing unit or the center wavelength of the light demultiplexed by the optical multiplexing / demultiplexing unit is shorter than a predetermined set wavelength. At least, the light multiplexing / demultiplexing unit is heated at a temperature equal to or higher than room temperature and equal to or lower than the glass transition temperature of the glass material for a predetermined heating time, so that light multiplexed / demultiplexed by the optical multiplexing / demultiplexing unit. The center wavelength of the light demultiplexed at the long wavelength side Wavelength correction method of an optical demultiplexer, characterized by correction. 2. A first slab waveguide is connected to an output side of one or more optical input waveguides arranged side by side, and the first slab waveguide is connected to an output side of the first slab waveguide. A plurality of arrayed waveguides having different lengths for transmitting light derived from the array waveguides are connected, and a second slab waveguide is connected to an output side of the plurality of arrayed waveguides. The slab waveguide has a waveguide pattern formed by connecting one or more optical output waveguides arranged in parallel on an output side thereof, and an array waveguide in which an optical multiplexing / demultiplexing unit is formed by the array waveguide. 2. A wavelength of the optical multiplexer / demultiplexer, wherein the wavelength of the light multiplexed or demultiplexed by the arrayed waveguide is corrected using the wavelength correction method according to claim 1. Correction method. 3. A first directional coupler is connected to an output side of the optical input waveguide, and light emitted from the first directional coupler is connected to an output side of the first directional coupler. Are connected to each other, and a second directional coupler is connected to the emission side of the two arm waveguides, and the second directional coupler is connected to the output side of the two arm waveguides. The output side of the sexual coupler has a waveguide pattern formed by connecting an optical output waveguide, and the Mach-Zehnder interference type element in which an optical multiplexing / demultiplexing unit is formed by the arm waveguide is an optical multiplexing / demultiplexing device. A wavelength correction method for an optical multiplexer / demultiplexer, wherein the wavelength of light multiplexed or demultiplexed by an arm waveguide is corrected using the wavelength correction method according to claim 1. 4. An optical input waveguide and an optical output waveguide are connected to a ring optical waveguide formed of a glass material via a directional coupler, and the resonance wavelength of the ring optical waveguide is adjusted by the ring optical waveguide. With a ring resonator type filter that is proportional to the length of the waveguide and the effective refractive index of the ring type optical waveguide,
A wavelength correction method for an optical multiplexer / demultiplexer that demultiplexes light having a wavelength different from the resonance wavelength of the ring-type optical waveguide from light having a plurality of different wavelengths, wherein the resonance wavelength of the ring-type optical waveguide is predetermined. By heating at least the ring-shaped optical waveguide at a temperature equal to or higher than room temperature and equal to or lower than the glass transition temperature of the glass material for a predetermined heating time when the wavelength is shorter than the set wavelength, the ring-shaped optical waveguide is formed. A wavelength correction method for an optical multiplexer / demultiplexer, wherein the resonance wavelength is corrected to a longer wavelength side. 5. A Fabry-Perot etalon in which mirrors are provided on both sides sandwiching a substrate formed of a glass material and the reflection surfaces of these mirrors are opposed to each other, and the resonance wavelength of the Fabry-Perot etalon is A wavelength correction method for an optical multiplexer / demultiplexer that splits light having a wavelength different from the resonance wavelength of the Fabry-Perot etalon from light having a plurality of wavelengths different from each other and is proportional to a distance between reflection surfaces and an effective refractive index of the substrate. Thus, when the resonance wavelength of the Fabry-Perot etalon is on the shorter wavelength side than a predetermined setting wavelength, at least the Fabry-Perot etalon is predetermined at a temperature equal to or higher than room temperature and equal to or lower than the glass transition temperature of the glass material. A wavelength compensator for an optical multiplexer / demultiplexer, wherein the resonance wavelength of the Fabry-Perot etalon is corrected to a longer wavelength side by heating for a heating time. Right way.